First-principles study of structure, electronic properties and stability of tungsten adsorption on TiC(111) surface with disordered vacancies

In this paper, we systematically investigate the atomic structure, electronic and thermodynamic properties of adsorbed W atoms on the polar Ti-terminated TixCy(111) surface with different configurations of adsorptions using first principle calculations. The bond length, adsorption energy, and formation energy for different reconstructions of the atomic structure of the W/TixCy(111) systems were established. The effect of the tungsten coverage on the electronic structure and the adsorption mechanism of tungsten atom on the TixCy(111) are also investigated. We also suggest the possible mechanisms of W nucleation on the TixCy(111) surface. The effective charges on W atoms and nearest-neighbor atoms in the examined reconstructions were identified. Additionally, we have established the charge transfer from titanium atom to tungsten and carbon atoms which determine by the reconstruction of the local atomic and electronic structures. Our calculations showed that the charge transfer correlates with the electronegativity of tungsten and nearest-neighbor atoms. We also determined the effective charge per atom of titanium, carbon atoms, and neighboring adsorbed tungsten atom in different binding configurations. We found that, with reduction of the lattice symmetry associated with titanium and carbon vacancies, the adsorption energy increases by 1.2 times in the binding site A of W/TixCy systems.